is it possible to go down one level in hash without knowing the key? (and without loop iteration of course)

for example: i have value in $hash->{'PARENT_KEY'}->{'KEY1'} also have more values from $hash->{'PARENT_KEY'}->{'KEY2'} $hash->{'PARENT_KEY'}->{'KEY3'} ...

i get the $hash output from some query, at the first lvl of the hash there is the PARENT_KEY and i don't know what it is, but at this lvl there will be only one key every-time, and i also doesn't care what it will be..

is there anyway to call the first key element or something? $hash->{0}->{'KEY1'} $hash->{0}->{'KEY2'}